Method of sizing paper



Patented Feb. 13, 1923.

UNHTED STATES PATENT OFFICE.

JUDSON A. DE CEW, OF NEW YORK, N. Y., ASSIGNOR TO PROCESS ENGINEERS, INC., A CORPORATION OF NEW YORK.

METHOD OF SIZING PAPER.

No Drawing.

To all whom it may concern Be it known that JUnsoN A. DE CEW, a citizen of the Dominion of Canada, residing at New York city, State of New York, has

invented new and useful Improvements in Methods of Sizing Paper, of which the following is a specification.

The purpose of this invention is to obtain not only proper sizing results in book paper and the like, which is heavily loaded with china clay or other fillers, but also .to in crease the amount of retention of the filling matter used. -The ordinary practice in paper mills is to treat the paper stock with the sizing material in the beating engine and then coagulate this with aluminum sulphate, the precipitated aluminum resinate distributing itself over the fibres so that when the paper is dry the natural capillarity of the fibres is largely destroyed and they become water and ink repellent.

When any inorganic loading material is used such as china clay, calcium sulphate or talc, it is added to the beating engine either before or after the sizing, in such a manner that there is very little opportunity for the filling material to come in contact with unprecipitated sizing solutions. As a result, the unsized filler merely becomes entrapped in the mass of precipitate but the grains or particles of clay or other filler are not themselves coated with the size. Even when the filler is added to the beating engine before the size is added, there is very little sizing action upon the filler itself because there is generally; sufficient coagulating action with the water in the beaters to precipitate the sizesolutions before they can react upon the clay.

portant improvement in the sizing effect can be obtained by allowing the diluted size to react completely with the filling material before it is added to the beating engine and the method will be carried outas follows The clay or similar material is mixed with Water in a tank previous to its use in the paper mill. Then add to these dilute suspensions, a rosin size which is preferably a highly dilute free rosin soap solution. While these materials are being mixed in the agitating tanks, a physico-chemical reaction takes place be- I have discovered, however, that an im provided with an agitator,

Application filed October 21, 1919. Serial No. 332,273.

tween the size and the clay which is called adsorption.

By this reaction, the soda in the size is partially taken up by the filler by chemical attraction and the resinous matter surroundmg each particle of clay is rendered less soluble so that a considerable portion of the size will be held to the surface of the clay particles.

When the dilute mixture of size and clay is added to the beating engine, the size which is not taken up by the clay will distribute itself over the pulp fibres so that in the end the clay and cellulose fibres will be equally water repellent. The reaction between the size and the clay will be greater when there is more free rosin in the size solutions and I have found out by actual mill tests that paper sized in this manner is more water resistant than those in which nearly all of the size is spread over the pulp fibres alone.

The reason that clay has never previously been sized in practice, is the fact that it is generally assumed that the clay could be sized in 'the beating engine but it is now shown that this rarely takes place and that only a portion of the clay would receive any sizing effect by present methods of operation. Y

The adsorption of size by the clay requires a little time to complete the reaction so it is only possible to effect a complete reaction by separate treatment. This process is especially valuable where there are adverse sizing conditions due to chemical impurities in the beater because once the clay is sized it will produce some sizing effect in the paper even if the fibres themselves are not properly sized.

What I claim is:

1..A method of sizing loaded paper stock, which consists in treating the filling material while in suspension in water, with a dilute colloidal aqueous solution of a free rosin size, mixing the materials until physical reactions take place as described, and adding the product to the paper stock in the beating engine.

2. A method of sizing loaded papers, which consists in sizing the filler and paper stocks separately, the filler being sized in aqueous suspension by mixing into it a dilute equeous. solution of a free rosin size.

The partially-sized filler is then added to the manner that a portion of the rosin will adpmper stock which is then also sized in the here to the filler bythe physical phenomenon 10 same manner, the size being finally precipiof adsorption, before the filler is mixed with teted by the addition of sulphate of alu the paper stock.

5 mine. In testimony whereof, have signed'my I 3. Amethod of sizing loaded papers, which name to this specification this 20th day of consists in treating the filling material, with October, 1919.

a dilute solution of free rosin size, in such a JUDSON A. DE CEW. 

